A
laser amplifier includes a
laser active slab with a source of pump power to amplify an input
laser beam, the laser active slab including a block of laser active material having opposed lateral faces defining a wedge lateral
dihedral angle, opposed longitudinal faces, and opposed parallel transverse faces, the wedge lateral
dihedral angle specified to minimize parasitic
amplified spontaneous emission. The source of pump power may be one or more
laser diode bars and microlenses producing a
gain sheet in the laser active slab. The lateral faces may include optical coatings highly transmitting at a
wavelength of the pump power and highly reflecting at a
lasing wavelength to provide a folded path for the input laser beam though the
gain sheet. The laser
amplifier may optionally include one or more external mirrors highly reflecting at the
lasing wavelength positioned and oriented to provide one or more additional zig-zag passes through the
gain sheet for the input laser beam and to provide a multi-pass-amplified laser beam.